The present invention relates to a pressure-sensitive element which is used as, for example, the switching element of a keyboard switch. More particularly, it relates to a pressure-sensitive element whose resistance value is varied stably and with good reproducibility by a pressure.
A prior-art pressure-sensitive element has been such that electrically-conductive particles are dispersed in an electrically-insulating elastic material such as rubber. The conduction mechanism of this pressure-sensitive element is as stated below. When the pressure-sensitive element is compressed by applying a pressure thereto, the conductive particles dispersed in the elastic material come into contact with one another, to form a conduction path. In addition, when the applied pressure is removed, the conductive particles return into the dispersed state, to restore the electrically-insulated state. In general, the pressure-sensitive element has a varying resistance range from an insulating state of a resistivity higher than 10.sup.7 .OMEGA.cm, to a conductive state of a resistivity lower than 10.sup.3 .OMEGA.cm.
The resistance variation of the prior-art pressure-sensitive element depends upon the approach and contact of the conductive particles in the pressed part. This leads to the disadvantages that the resistance value versus the pressure disperses greatly and that the reproducibility is poor.